1. Field of Application
This invention relates to a device for monitoring belt speed and movement for bulk material conveyor systems, and more particularly to underspeed, overspeed and slip detectors for conveyor belts and other material moving components of such systems and to a zero speed switch.
2. Description of Prior Art
Bulk material handling conveyor systems usually include at least one belt conveyor which receives bulk material, such as coal, iron ore, cement, etc. to transport same between locations removed, one from the other, for the purpose of stocking, processing, shipping, or other required handling incident to the use of the bulk material. Such systems may also include: multiple conveyors located in a collinear fashion (which may be referred to as upstream and downstream conveyors); conveyors which co-operate to move material in two different directions (which may be referred to as a main conveyor and a shuttle conveyor); and a conveyor co-operating with a bulk material elevator for changing the level of material flow.
The increasing demand for large, highly complex and high speed bulk material conveyor systems has created a need for more effective control devices to detect malfunctions in such systems, and protect the expensive mechanical components required in such systems. Unfortunately presently available control systems are few in number, are high in cost, are usually designed for a particular system and thus lack the versatility to permit use thereof with another system without significant re-design and modifications, and quite often provide inoperable solutions.
Rotech manufactures speed measuring rollers which have a roller mounted on an arm which is biased against the underside of a conveyor belt. It has an encoder associated with such roller for belt speed measurement, slip detection, stop detection, belt weighers, belt interlocking and belt indexing. A problem with this type of sensing is that it adds additional parts instead of being a substitute for an existing roller as is the intention of the present invention.